1 files changed, 142 insertions, 0 deletions
diff --git a/arm9/lib/src/OS_mutex.c b/arm9/lib/src/OS_mutex.c
new file mode 100644
index 00000000..5eb999a9
--- /dev/null
+++ b/arm9/lib/src/OS_mutex.c
@@ -0,0 +1,142 @@
+#include "nitro/types.h"
+#include "function_target.h"
+#include "OS_mutex.h"
+#include "OS_system.h"
+
+ARM_FUNC void OS_InitMutex(OSMutex *mutex)
+{
+    OS_InitThreadQueue(&mutex->queue);
+    mutex->thread = NULL;
+    mutex->count = 0;
+}
+
+ARM_FUNC void OS_LockMutex(OSMutex *mutex)
+{
+    OSIntrMode prevIntrMode = OS_DisableInterrupts();
+    OSThread *currentThread = OS_GetCurrentThread();
+
+    OSThread *ownerThread;
+    for (;;)
+    {
+        ownerThread = ((volatile OSMutex *)mutex)->thread;
+
+        if (ownerThread == NULL)
+        {
+            mutex->thread = currentThread;
+            mutex->count++;
+            OSi_EnqueueTail(currentThread, mutex);
+            break;
+        }
+        else if (ownerThread == currentThread)
+        {
+            mutex->count++;
+            break;
+        }
+        else
+        {
+            currentThread->mutex = mutex;
+            OS_SleepThread(&mutex->queue);
+            currentThread->mutex = NULL;
+        }
+    }
+
+    (void)OS_RestoreInterrupts(prevIntrMode);
+}
+
+ARM_FUNC void OS_UnlockMutex(OSMutex *mutex)
+{
+    OSIntrMode prevIntrMode = OS_DisableInterrupts();
+    OSThread *currentThread = OS_GetCurrentThread();
+
+    if (mutex->thread == currentThread && --mutex->count == 0)
+    {
+        OSi_DequeueItem(currentThread, mutex);
+        mutex->thread = NULL;
+
+        OS_WakeupThread(&mutex->queue);
+    }
+
+    (void)OS_RestoreInterrupts(prevIntrMode);
+}
+
+ARM_FUNC void OSi_UnlockAllMutex(OSThread *thread)
+{
+    OSMutex *mutex;
+    while (thread->mutexQueue.head)
+    {
+        mutex = OSi_RemoveMutexLinkFromQueue(&thread->mutexQueue);
+
+        mutex->count = 0;
+        mutex->thread = NULL;
+        OS_WakeupThread(&mutex->queue);
+    }
+}
+
+ARM_FUNC BOOL OS_TryLockMutex(OSMutex *mutex)
+{
+    OSIntrMode prevIntrMode = OS_DisableInterrupts();
+    OSThread *currentThread = OS_GetCurrentThread();
+    BOOL locked;
+
+    if (mutex->thread == NULL)
+    {
+        mutex->thread = currentThread;
+        mutex->count++;
+        OSi_EnqueueTail(currentThread, mutex);
+        locked = TRUE;
+    }
+    else if (mutex->thread == currentThread)
+    {
+        mutex->count++;
+        locked = TRUE;
+    }
+    else
+    {
+        locked = FALSE;
+    }
+
+    (void)OS_RestoreInterrupts(prevIntrMode);
+    return locked;
+}
+
+ARM_FUNC void OSi_EnqueueTail(OSThread *thread, OSMutex *mutex)
+{
+    OSMutex *prev = thread->mutexQueue.tail;
+
+    if (!prev)
+    {
+        thread->mutexQueue.head = mutex;
+    }
+    else
+    {
+        prev->link.next = mutex;
+    }
+
+    mutex->link.prev = prev;
+    mutex->link.next = NULL;
+    thread->mutexQueue.tail = mutex;
+}
+
+ARM_FUNC void OSi_DequeueItem(OSThread *thread, OSMutex *mutex)
+{
+    OSMutex *next = mutex->link.next;
+    OSMutex *prev = mutex->link.prev;
+
+    if (!next)
+    {
+        thread->mutexQueue.tail = prev;
+    }
+    else
+    {
+        next->link.prev = prev;
+    }
+
+    if(!prev)
+    {
+        thread->mutexQueue.head = next;
+    }
+    else
+    {
+        prev->link.next = next;
+    }
+}